Radio frequency (RF) signals from the millimeter (mm)-wave spectrum (e.g. V Band, E Band, W Band, etc.) have been in use in military applications as well as a growing number of consumer applications. For example, automotive electronic safety systems, such as collision-avoidance radar systems, operate at frequencies from the mm-wave spectrum. Further, the allocation of mm-wave bands for upcoming fifth-generation (5G) cellular wireless communications systems is expected to vastly increase the use of available wide bandwidths in support of communications and entertainment services to be offered to consumers by service providers. Testing these higher-frequency mm-wave systems requires suitable test equipment with not only sufficient frequency range but also sufficient acquisition bandwidth.
A vector signal analyzer is an instrument that measures the magnitude and phase of an input signal at a frequency within the intermediate frequency (IF) bandwidth of the instrument. Many measuring instruments, such as vector signal analyzers, employ a quadrature demodulator that provides an in-phase (I) signal and a quadrature (Q) signal that are exactly 90° out of phase. The I and Q signals are vector quantities and the amplitude and phase shift of a signal received in response to, for example, to a test signal transmitted to a device under test (DUT) can be calculated based on the I and Q signals. The demodulator generates a sum and difference term for analysis by the vector signal analyzer. However, to generate a usable IF signal, a mm-wave signal received at a transceiver of an instrument must be downconverted.
Existing millimeter (mm)-wave IQ demodulators for vector signal analyzers have many imperfections and are often some combination of expensive, bulky, heavy, unwieldy, or limited in IF/RF bandwidth and physical reach.